Paper sending mechanism with a dynamically adjustable paper-feeding angle

ABSTRACT

A paper sending mechanism with a dynamically adjustable paper-feeding angle has a torsion spring installed at the bottom of a paper tray. The first spring arm of the torsion spring is connected to a printing device, and the second spring arm is attached to the bottom of the paper tray. The torsion spring controls the tilting angle of the paper tray according to the number of papers inside the paper tray. It has the advantage of a low production cost and accurate paper-feeding angle adjustment.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a paper sending mechanism and, in particular, to a paper sending mechanism that dynamically adjusts the paper-feeding angle according to the number of papers inside a paper tray.

2. Related Art

Most offices use a lot of papers for printing, copying or faxing various kinds of documents and letters. In generally, commonly seen business machines such as copiers require the feeding of papers for printing. The printing quality and operation efficiency are the focusing concerns of the manufacturers of business-related machines.

In these business machines, how to avoid paper jams and how to pick accurately single piece of paper are the important research directions in the development of paper transmission devices. Related techniques have been disclosed in, for example, FIG. 1 shows an automatic paper-feeding roller pressure adjusting mechanism. As shown in FIG. 1, the mechanism is characterized in that a plate 110 is provided under a paper tray 100. Both ends of the plate 110 are installed with a first spring 120 and a second spring 130 connected to the paper tray 100. A supporting point 140 is provided in the middle section of the plate 110. As the plate 110 functions as a lever and the first spring 120 and the second spring 130 deform, the pressure between the paper-separating roller and the paper-separating chip is adjusted to control the paper-feeding angle of the paper tray 100.

The U.S. Pat. No. 4,212,456 uses a paper tray installed with an axis in the middle section under it. Thus, the paper tray can rotate relative to the printing device. An elastic plate is provided under the paper tray. A pressure spring is installed at the paper entrance in front of the paper tray. The paper-feeding angle is thus adjusted by the elastic plate and the pressure spring. The U.S. Pat. No. 5,718,424 has a paper-feeding roller and a rotatable pressure plate installed at the paper entrance of the paper tray. One end of the pressure plate is installed with an elastic device. As paper pushes the pressure plate that drives the elastic device, the paper-feeding roller and the pressure plate form different paper-feeding gaps.

SUMMARY OF THE INVENTION

The invention improves the action principles of the above-mentioned prior art. The specification provides a paper sending mechanism with a dynamically adjustable paper-feeding angle, which paper sending mechanism has fewer component devices, simpler and more direct actions, lower production costs, and a design for easier assembly and maintenance.

The disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle can be used in printers, fax machines, scanners, and multi-function peripherals (MFP). It comprises a paper tray, paper-feeding roller, a paper-separating plate, and a torsion spring. The paper tray can accommodate several pieces of paper for printing, and has a paper entrance. The bottom of the paper tray is extended out with a suspension arm that is pivotally connected to a printing device, so that the paper tray can rotate relative to the printing device. The paper-feeding roller and the paper-separating plate are installed and are adjacent to the paper entrance of the paper tray. The paper-separating plate picks up a piece of paper through the paper-feeding roller, and feeds it into the printing device. The torsion spring includes a first spring arm and a second spring arm. Due to an elastic force, the second spring arm has a specific angle with respect to the first spring arm. The first spring arm is connected to the printing device, and the second spring arm touches the bottom of the paper tray.

When the papers in the paper tray get fewer and fewer because of being used, the angle between the second spring arm and the first spring arm gradually increases, and thus the paper tray also rotates, by using the suspension arm as its center, with respect to the printing device. Therefore, if there are more papers inside the paper tray, its angle is flatter. If the papers inside the paper tray get fewer and fewer because of being used, then the second spring arm in touch with the paper tray experiences less weight from the papers, so that the angle between the first spring arm and the second spring arm increases to push the paper tray. In this case, the paper tray has a steeper paper-feeding angle, and is much easier for the paper therein to enter the paper-separating region.

The disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle uses a torsion spring, which does not require any other component to produce action and which is installed in a manner that is in direct contact with the bottom of the paper tray. Its action contact surface is more direct and complete. It can more rapidly and accurately react to the amount of papers inside the paper tray in order to dynamically adjust the paper-feeding angle. Thus, the invention can avoid incorrect paper picking.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the detailed description given hereinbelow illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a schematic view of a conventional paper sending device;

FIG. 2 is a schematic view of the first action of the disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle; and

FIG. 3 is a schematic view of the second action of the disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle.

DETAILED DESCRIPTION OF THE INVENTION

The disclosed paper sending mechanism with a dynamically adjustable paper-feeding angle is shown in FIGS. 2 and 3. It can be used in printers, fax machines, scanners, and multi-function peripherals (MFP). The invention comprises a paper tray 10, paper-feeding roller 20, a torsion spring 30, and a paper-separating plate 40. The paper tray 10 accommodates several pieces of papers 60 for printing and has a paper entrance 11 for the paper to enter a printing device (not shown). The bottom of the paper tray 10 is extended out with a suspension arm 12 that is pivotally connected to the printing device, so that the paper tray 10 can rotate relative to the printing device. The paper-feeding roller 20 is covered with a rubber layer to increase the friction for picking paper 60. The paper-feeding roller 20 is installed at the vicinity of the paper entrance of the paper tray 10. The paper-separating plate 40 is installed at the vicinity of the paper entrance 11 of the paper tray 10, corresponding to the paper-feeding roller 20 in order to pick papers 60 into the printing device. Another side of the paper-separating plate 40 is connected with an elastic device 50 for pushing the paper-separating plate 40, so that the paper-separating plate 40 is in constant contact with the paper-feeding roller 20. The torsion spring includes a first spring arm and a second spring arm. The first spring arm is in contact with the printing device and restricted by a stopper 80. The second spring arm 32 is in touch with the bottom of the paper tray 10. The first spring arm 31 and the second spring arm 32 have a specific relative angle 33. There is not limitation on where the torsion spring 30 is installed. FIG. 2 shows a preferred embodiment. An axis 70 is installed in the printing device for the installation of the suspension arm 12, the paper-feeding roller 20, and the torsion spring 30. In fact, the axis 70 can be formed on the suspension arm for the installation of the torsion spring 30. The invention does not limit the installation positions of the axis 70 and the torsion spring 30.

With further reference to FIG. 3, as the papers 60 in the paper tray 10 get fewer and fewer as being used, the angle 33 between the second spring arm 32 and the first spring arm 31 gradually increases, thereby raising the paper tray 10. The paper tray 10 thus rotates with respect to the printing device using the axis in connection with the suspension arm 12 as its center. The rotation angle of the paper tray 10 increases with the angle 33. Therefore, if there is more papers 60 inside the paper tray 10, the paper-feeding angle 95 between the paper tray 10 and the level surface 90 is flatter. If the papers 60 inside the paper tray 10 reduces with its usage, the second spring arm 32 in touch with the paper tray 10 experiences less weight from the papers 60. The angle between the first spring arm 31 and the second spring arm 32 increases to push the paper tray 10. In this case, the paper tray 10 has a steeper paper-feeding angle 95 with respect to the level surface 90, easier for the papers 60 therein to enter the printing device.

The torsion spring 30 of the disclosed paper sending mechanism with a dynamically adjustable angle is in direct contact with the bottom of the paper tray 10. Therefore, the torsion spring 30 can more rapidly and accurately react to the number of papers 60 stored inside the paper tray 10. The paper-feeding angle 95 is thus dynamically adjusted to avoid incorrect paper-feeding.

Certain variations would be apparent to those skilled in the art, which variations are considered within the spirit and scope of the claimed invention. 

1. A paper sending mechanism with a dynamically adjustable paper-feeding angle for a printing device, the paper sending mechanism comprising: a paper tray, which accommodates a plurality of pieces of papers, has a paper entrance formed on one side, and extends from the paper tray bottom a suspension arm pivotally connected to the printing device for the paper tray to rotate with respect to the printing device; a paper-feeding roller, which is installed at the vicinity of the paper entrance of the paper tray; a paper-separating plate, which is installed at the vicinity of the paper entrance of the paper tray in a movable way to pick, through the paper-feeding roller, a piece of the paper into the printing device; and a torsion spring, which has a first spring arm and a second spring arm, the second spring arm having an angle with respect to the first spring arm due to an -elastic force; wherein the first spring arm is installed in the printing device and the second spring arm is in contact with the bottom of the paper tray so that when the papers accommodated inside the paper tray get fewer and fewer as being used, the angle between the second spring arm and the first spring arm increases to raise the paper tray by rotating with respect to the suspension arm, thereby increasing the paper-feeding angle of the paper tray with respect to the printing device.
 2. The paper sending mechanism with a dynamically adjustable paper-feeding angle of claim 1, wherein the printing device contains an axis for the installation of the torsion spring.
 3. The paper sending mechanism with a dynamically adjustable paper-feeding angle of claim 1, wherein the suspension arm contains an axis for the installation of the torsion spring.
 4. The paper sending mechanism with a dynamically adjustable paper-feeding angle of claim 1, further comprising an elastic device installed on one side of the paper-separating plate for the paper-separating plate to be regularly in contact with the paper-feeding roller.
 5. The paper sending mechanism with a dynamically adjustable paper-feeding angle of claim 1, wherein the paper-feeding roller is covered with a rubber layer.
 6. The paper sending mechanism with a dynamically adjustable paper-feeding angle of claim 1, wherein the printing device has a stopper to restrict the first spring arm. 